Invalid people confined to wheelchairs usually like to be as independent as possible and some of them are reluctant to travel because they do not appreciate having to rely on other persons to transfer them from their wheelchair to the vehicle. Lift devices for lifting wheelchairs into vehicles have been previously provided. However, the mechanisms of such lift devices have been rather complicated and expensive. Some of them also occupy a lot of space in the interior of the vehicle such that the loading capacity of the vehicle is greatly reduced.